Personal containment systems can protect a user from a variety of harmful chemical or biological agents. Many examples of personal containment systems that can surround a user are known, such as protective suits, protective tents, casualty bags for injured persons, and the like. These systems preferably isolate the user's entire body from contaminants. Often, the contaminants include respiratory hazards, and the systems must employ air delivery systems so that the user is able to breathe when isolated from the environment. Respirators are often used in conjunction with personal protection systems to provide the user with purified air. A variety of respirators are known and described below.
Certain personal containment systems employ a non-powered purifying respirator. Air is drawn into the system through a filter by the user's breathing action. When the user draws a breath, negative pressure is created in the system and air is drawn in through the filter. When the user expels a breath, spent air leaves the system through a valve.
A powered air-purifying respirator (PAPR) can be employed to supply a continuous stream of filtered air under positive pressure to a personal containment system. A typical PAPR includes a filter attached to a blower which delivers filtered air to the system. Such air delivery can involve a conduit that ducts air to a hood or a spigot on a protective garment. PAPRs are generally powered by a battery. When used with a protective garment, the PAPR blower typically is mounted on a belt wrapped around a user's waist or on a harness strapped to the user's torso, and worn externally. PAPRs are generally employed in industrial applications where the environmental hazards are well defined and quantified.
A self-contained breathing apparatus (SCBA) is another variety of respirator employed as a part of a personal containment system. A SCBA typically supplies air or oxygen from a portable source to a regulator or other breathing device worn by the user. A SCBA worn inside a sealed protective suit provides the user with a fully contained protective environment. SCBA systems employed in this manner can be used when the nature of the hazard is not known, or in environments that might be void of oxygen.